It is desirable to be able to provide a suspension of ice crystals having an average crystal size which is as small as possible.
Conventionally the suspension of ice crystals is manufactured in a scraped surface heat exchanger (SSHE). This process mixes and cools the aqueous solution of sugars simultaneously. A disadvantage of this process is that there is a temperature gradient between the wall of the SSHE and the centre, thus crystallisation is localised at the wall of the SSHE. This results in uneven crystal distribution.
A further disadvantage of using a SSHE to provide the ice crystal suspension is that a SSHE is an expensive piece of equipment.
Alternatively the suspension of ice crystals may be manufactured via quiescent freezing process within, for example, a lolly mould. Crystallisation occurs at the walls of the mould with growth of large, dendrite crystals into the centre of the product.
We have now been able to devise a simple process for producing the suspension of ice crystals, whereby ice crystals having the desirable small crystal size are produced. Furthermore, the process permits the formation of a large number of evenly distributed crystal nuclei. The process involves initially, individually cooling a first solution of concentrated sugar and a second solution of water or a less concentrated sugar solution prior to mixing the cooled solutions.